In cutting devices for cutting paper or the like, there is “push cutting”, in which a cutter is pushed in a direction perpendicular to the edge of the blade when cutting, and “pull cutting”, in which the cutter is pushed while moving parallel to the edge of the blade when cutting. For example, in JP-A-2001-88084 and the like, a method is employed that emphasizes the latter “pull cutting”, in which the edge of the cutter blade bites slightly into a blade receiving surface of a receiving part, and at the same time, in order to improve sharpness, the paper is cut while moving parallel to the blade receiving surface.
When cutting paper using the “pull cutting” described above, material is used for a blade receiving surface 41 such that an edge 44 of a cutter 43 bites into the blade receiving surface 41 of a receiving part 40 as shown in FIG. 5. This is because if a hard blade receiving surface 41 into which the blade edge 44 could not bite were used, the blade edge 44 of the cutter 43 would very quickly become unable to cut. Therefore, a slight groove 42 is formed in the blade receiving surface 41 by the blade edge 44 of the cutter 43.
Typically, taking into consideration “undulation” of the blade edge 44, unevenness of the blade receiving surface 41 and so forth, the bite is set to a depth of approximately 0.3 mm to 0.7 mm. Moreover, in order to allow the blade edge to bite, metal or the like having a large elastic modulus cannot be used for the material used for the blade receiving surface of the receiving part, and typically a resin such as polypropylene (PP) is used.
However, when the cutter is moved parallel to the blade receiving surface with the blade edge biting in, the blade receiving surface of the receiving part deforms in the direction of movement of the cutter by the friction exerted thereon.
FIGS. 6A and 6B illustrate the deformation of the receiving part 40 when the cutter 43 moves parallel to the blade receiving surface with the blade edge biting into the blade receiving surface 41 of the receiving part 40. At this point, although the receiving part 40 is fixed in place at both ends, when the cutter 43 moves in the direction of the arrow with the blade edge 44 biting in, one region A extends and deforms while an opposite region B contracts and deforms, the two regions divided along a center. If the material of the resin receiving part 40 is polypropylene (PP), its elastic modulus is approximately 1/100 that of steel, or from 103 to 104 kg/cm2. As a result, if the length of the receiving part 40 is 300 mm, then at the center a positional displacement of 0.4 mm to 0.8 mm appears.
Consequently, the deformation described above causes wrinkles to appear in 1-2 sheets of paper in the vicinity of the receiving part 40. If, for example, the cutting device is built into a copy machine, then when cutting the paper immediately after copying, if wrinkles appear in the paper, the copy surface might be disrupted, causing text or figures to be blurred, other paper surfaces to be sullied, and so forth.